Off-grid generator battery charging setup

[goodlime]

So as I get closer to moving out to the homestead to start building, I'm having to get really specific on some systems design. Power being a key one.

The homestead is completely off-grid. No systems exist on the property currently. All that is out there is an old stone building and 100+ olive trees.

I want to create a power system that I can add on to in a modular fashion. Starting with a generator, charge controller, inverter and batteries.

I'm pretty much set on buying an SDMO SD6000E Diesel. It's powered by a Yanmar L100 10 HP engine, and has been recommended to me by a lot of people. This is great, a little pricey, but should last for years and years with proper maintenance. Also, I can run it on agricultural diesel, meaning there is no tax on the fuel (a big deal in Europe).

The challenge with this is that the generator only outputs a modified sine wave, and that's no good for computers and TVs and such. Since I rely on all this high-tech stuff to make a living, I want to make sure it's protected from dirty energy and power spikes.

This means that I need to introduce another layer to the system. Also due to the fact that running a generator whenever you need to use any power will waste a lot of fuel and be very noisy.

Adding a battery bank, charge controller and pure sine inverter will mean we can have power all the time, while just running the generator when the batteries need charging, or when there is a heavier load on the system. I will need a automatic transfer switch to kick on the genset when the batteries are waning.

This will be great for the first phase. But once we have an actual building, the power requirement will increase, and there will be a place to permanently fix some solar panels. The building will face due south, so the roof will be ideal for PV.

I want the initial system to be able to bolt on solar, and maybe wind, without having to mothball any existing components.

Lighting will be 12v LED variety. I'm assuming you can connect straight to the batteries, providing they are in a 12v configuration. The rest of the system will run standard European outlets at 240v.

I'm finding it quite a challenge to locate information on precise equipment that will be suitable for this requirement. Does anyone have any experience with this stuff?

[BoatGuy]

A lot has been written about how computers won't get along with a modified sinewave output, and that idea has been used as marketing point for several inverter manufacturers. I understand the "problem" that they are proposing and I have no doubt that there are probably several pieces of equipment out there that have really had problems with them.

Now, here's my real-world experience... it has never caused me any problems and I have used a LOT of different inverters in trucks and vessels. I used to travel extensively and would often have 2 or 3 inverters with me, to charge cell phones and to power laptops and netbooks. The only problem I have ever seen is that caused by a ground loop between two different pieces of equipment that were hooked to two different inverters (this is a pretty common problem if you are going to be using more than one inverter, and I don't recommend letting the circuits of two different inverters intermingle in any way. If the ground loop is severe enough, it can create a safety hazard. For example, I wouldn't power a tv set on one inverter and a dvd player on another, since there are wires connecting the two devices).

All of my inverters (except for an old Trace inverter that I rarely use) produce a modified sine wave. On them, I have charged cellphones, run computers, tvs, dvd players, satellite systems, etc and never experienced a service problem or a lifetime problem. The only failure mode I ever saw was from impact when I didn't tie it down well enough.

Anyway, that's been my experience. Your's may vary, since I never have used 50 Hz equipment, which I believe is standard in europe. I can't see how it would make a difference though. The one place where I might have a concern, is with a relatively old computer system, that didn't use a switching power supply. I can see where that might make it more susceptible to RF interference.

If you do have problems, you may want to investigate the use of an Uninterruptible Power Supply, which often has a large transformer that can clean up "dirty" electricity and insulate the equipment from the supply. In the U.S., some of those built by APC are pretty good, and fairly inexpensive.

FWIW, even though the 12 v lighting can be connected directly to the batteries, I would still determine what current level is running through each leg at full load, then fuse it accordingly. Even a 1 amp circuit can cause a fire, if a short somehow developes. Those batteries are capable of putting out a couple of hundred amps (or more) each and if short occurs, it will melt that wiring in a heartbeat.

One more thing I would give some consideration is how you are going to "plug in" to the 12 v system. A lot of 12 volt equipment comes with cigarette lighter attachments. While this is probably fine for the low current stuff, they are prone to popping out at inopportune moments and they are only good up to about 10 amps. Even before you reach 10 amps, the contacts are poor enough that you will begin losing power to heat, which could cause a fire long-term and just increases the load on your battery bank in the short term. In ham radio, we tend to use PowerPole connectors, since they are VERY secure, last a long time and are impossible to plug in backwards (which would be VERY bad on a DC system). Anyway, just a thought...

[jakematic]

I work from home most of the time and can tell you my equipment did not like the square / modified sine wave at all.
One computer sounded like it was shorting out and 'burning' everytime the UPS kicked it.
That UPS now runs a lamp in the living room.

For the little bit of extra money it's not worth it to me to skip pure sine wave.

I use the APC UPS - the first model that has PS wave is the 5000 I think. About $500 here in the States.

Been thinking long and hard about this same issue when I go to my homestead.
Am inclined to just buy a larger data center UPS for the whole house backed by a generator, for the AC equipment.
Yes they are expensive, but so it cobbling together a bunch of batteries, an inverter, etc.

Distribution of 12V is still one of my hob-goblins for the same reason we use AC instead - length, resistance, etc.

I think the key to being off grid is trying to use things like a gas refrigerator, etc to eliminate as much need for AC as possible.
The lighting aspect still perplexes me though and kerosene lamps would be my choice if it weren't so darned expensive.

[BoatGuy]

I have considered putting a gas refrigerator out on a back porch, IF I could get a methane digester up and running. I dunno a lot about them yet, though. For instance, how well does the digester work in the winter? Of course, that is why I'd put the fridge on the back porch. In the summer, the digester could power it, and in the winter, the weather could. I'd just hate to lose my perishables due to a gas shortage.

[Hanzel]

A lot has been written about how computers won't get along with a modified sinewave output,

If anyone is scratching their heads... that means you will hear snap, crackle and pop and then all the magic smoke will leave the computers.  I work with a lot of dirty power.  We will use a Furman power conditioner in front of the UPS before it gets to the servers.  We hope that the first 2 will fry before the server gets it.  IF you think you will have dirty power or power that will go up and down, put something in front of your equipment first that will fry first like a good surge protector.  They go pop and smoke but you computer will be fine.

[goodlime]

I have considered putting a gas refrigerator out on a back porch, IF I could get a methane digester up and running. I dunno a lot about them yet, though. For instance, how well does the digester work in the winter? Of course, that is why I'd put the fridge on the back porch. In the summer, the digester could power it, and in the winter, the weather could. I'd just hate to lose my perishables due to a gas shortage.

I watched this video a while back, which gave me the same idea.

Biogas: From Insinkerator to Refrigerator (1 of 3)

I'd definatly like to build a biogas digester and run some appliance on methane. But, you know, baby steps. I gotta figure out how to power a lightbulb first!

[goodlime]

I spoke with a helpful guy at a solar company here in the UK about my requirements and did a ton of research into various products. I think I now have a much better idea as to how I'm going to configure my power system in a modular fashion, so I can add to it in stages.

Stage 1 - Base genverter system
Generator - something powered by a Yanmar L100 Diesel, such as SDMO SD6000E 6.5 Kva
Inverter/Charger - Outback VFX3024E
Batteries - flooded lead-acid deep cycle in series (reconditioned, about 45% of new cost)
DC-DC Converter - 24V to 12V, Step-down, 10A (for 12V lighting)
Inverter monitoring/control - Outback Mate

Stage 2 (adding to stage 1) - Add small amount of PV for maintainance charging and small daytime loads
Solar Charge controller - Morningstar Tristar (can later be used as DC load controller when we upgrade the solar)
PV Panels - 2 panels of approx 220W

Stage 3 (adding to stage 1 & 2) - Rounding out the system
Solar Charge Controller - Outback FM60
DC Load Controller - Re-purpose the Tristar, replacing with new charge controller
PV Panels - 6 panels (ideally to match the existing 2)
System link - Outback Hub (links the inverter and charge controller for better management)

Stage 4 - Strengthening the system
2nd battery bank (depending on time from stage 1, maybe 2 new sets)
PV Panels - 4-6 panels (ideally to match the existing


Stage 1 will fulfill the basic power requirements while living on site and building the house. I will use 12V LED lighting connected to the battery bank by the DC-DC converter. Ideally we would use a load controller, to prevent over discharge of the battery bank. Since the load from the 12V lighting will be very low and I'll be careful :-).

I've sourced some LED lights from Ikea for about $15. They are 3W and have a bendy neck. They come with a 2-pin DIN connector (like old speakers) that connects to the supplied 12V transformer. I'll build a circuit using some low cost project boxes and 2-pin DIN outlets. That way the system can be flexible and lights can be moved around as necessary.

I've have also found some 12V LED floodlights for the outside. These are 10W units and a supposed to equal a 100W halogen flood. In total my 12V yurt lighting system will be less than 40W, if all lights are on at once!

I will install standard 240V outlets to run off the inverter. All the cabling for AC and DC will run under the wooden platform the yurt sit atop of.

If I can afford it, I will do stage 1 and 2 together. Since I won't be on site for some extended periods, the addition of some solar will mean the generator can be disconnected (and locked away safely, so it doesn't sprout legs), and the batteries can be kept healthy by the solar panels performing a maintenance charge. The cost of stage 2 I'm estimating around $850-1000.

Stage 1 is where the bulk of the expenditure will be. That's looking at around $7500 right now. 60% of that cost is the generator, but I've had so much advise about not cheaping out on the generator if I want it to last. I'm not usually one for false economy.

The one area I'm willing to go a little cheap is on the batteries. Since this will be my first off-grid experience. I'd sooner learn with less expensive batteries that may have a shorter life, since I will probably make some mistakes along the way as I learn, that will shorten their life anyway!

[Johnny-Max]

sorry ice, I split the topic off into its own topic, I guess you were typing a response when I split it.

[icesphere]

No worries buddy, I can go off on tangent . I was lol I deleted it and shifted to new post at least I hoped I did it properly lol.

[goodlime]

I ordered the genset yesterday. I ended up going for a Pramac P4500 with electric start. To make the setup compatible with the 2 pole remote start/stop on the inverter/charger I plan to get I had to shell out an extra £400 (+ 20% VAT!) for a modified starter panel and its installation.

It came to around £2350 ($2650) all in, with shipping. I have to admit, it stung a little, especially knowing that this is just the first component of many.

I could have got a Honda genset running gasoline for half the price. But the generator I chose has a diesel engine, so will last longer and I can run it on agricultural (red) diesel.